Email

1

• Email

2
Mail Headers

• From andrea.schiavoni_at_securegroup.it Mon Aug 2
  111703 2004
• Return-Path ltandrea.schiavoni_at_securegroup.itgt
• Received from antigen.bucknell.edu
  (antigen.bucknell.edu 134.82.9.20) by
• marge.bucknell.edu (8.12.11/8.12.11) with
  ESMTP id i72FGQgR013512 for
• ltperrone_at_bucknell.edugt Mon, 2 Aug 2004
  111703 -0400 (EDT)
• Received from smtp-gtw.securegroup.it
  (dns.securegroup.it 217.57.152.35)
• by antigen.bucknell.edu (8.12.11/8.12.11)
  with SMTP id i72FFUqo013243 for
• ltperrone_at_bucknell.edugt Mon, 2 Aug 2004
  111531 -0400 (EDT)
• Received from mercurio.intranet.securegroup.it
• (mercurio.intranet.securegroup.it
  192.168.1.3) by smtp-gtw.securegroup.it
• (Postfix) with ESMTP id 09DF016000F Mon,
  2 Aug 2004 151520 0000 (GMT)
• Received from securegroup.it (localhost
  127.0.0.1) by
• mercurio.intranet.securegroup.it
  (Postfix) with ESMTP id 6D5EB1A4002 Mon,
• 2 Aug 2004 151519 0000 (GMT)
• Message-ID lt410E59C9.2040305_at_securegroup.itgt
• Date Mon, 02 Aug 2004 171209 0200
• From Andrea Schiavoni ltandrea.schiavoni_at_securegro
  up.itgt
• User-Agent Mozilla/5.0 (Windows U Windows NT
  5.0 en-US rv1.4)

• RFC 822 - messages have
• header
• body
• Both are represented in ASCII text. MIME types
  allow the message body to carry many kinds of
  data.

3
MIME Types /etc/mime.types

• This file controls what Internet media types
  are sent to the client for
• given file extension(s). Sending the correct
  media type to the client
• is important so they know how to handle the
  content of the file.
• Extra types can either be added here or by
  using an AddType directive
• in your config files. For more information
  about Internet media types,
• please read RFC 2045, 2046, 2047, 2048, and
  2077. The Internet media type
• registry is at lthttp//www.iana.org/assignments/
  media-types/gt.
• MIME type Extension
• application/EDI-Consent
• application/EDI-X12
• application/EDIFACT
• application/activemessage
• application/andrew-inset ez
• application/applefile
• application/atomicmail
• application/batch-SMTP
• application/beepxml
• application/cals-1840

audio/mpeg mpga mp2
mp3 audio/telephone-event audio/tone audio/x-aiff
aif aiff aifc audio/x-pn-realau
dio ram rm audio/x-realaudio
ra audio/x-wav
wav chemical/x-pdb
pdb chemical/x-xyz xyz image/bmp
bmp image/gif
gif image/jpeg jpeg
jpg jpe image/png
png image/tiff multipart/alternative multipart/di
gest multipart/encrypted multipart/form-data multi
part/mixed multipart/voice-message text/calendar t
ext/css css text/directory
text/enriched text/html
html htm text/plain asc
txt text/prs.lines.tag text/rfc822-headers text/ri
chtext rtx text/rtf
rtf video/mpeg
mpeg mpg mpe video/parityfec video/pointer video/q
uicktime qt mov
4
SMTP Session

• perrone_at_perrone /etc telnet carina 25
• Trying 134.82.56.130...
• Connected to carina.eg.bucknell.edu
  (134.82.56.130).
• Escape character is ''.
• 220 carina.eg.bucknell.edu ESMTP Sendmail
  8.12.10Sun/8.12.10 Wed, 27 Apr 2005 071236
  -0400 (EDT)
• HELO perrone.eg.bucknell.edu
• 250 carina.eg.bucknell.edu Hello
  perrone.eg.bucknell.edu 134.82.56.120, pleased
  to meet you
• MAIL FROM santaclaus_at_northpole.com
• 250 2.1.0 santaclaus_at_northpole.com... Sender ok
• RCPT TO perrone_at_eg.bucknell.edu
• 250 2.1.5 perrone_at_eg.bucknell.edu... Recipient ok
• RCPT TO dudemeister_at_bucknell.edu
• 250 2.1.5 dudemeister_at_bucknell.edu... Recipient
  ok
• DATA
• 354 Enter mail, end with "." on a line by itself
• Hey man, this is a bogus message... sorry.
• .
• 250 2.0.0 j3RBCa0B017875 Message accepted for
  delivery
• QUIT

5
Message Delivered
6
Details on Message
7
Message Encoding

• --_-1140908113_D
• Content-Transfer-Encoding base64
• Content-Disposition attachment filename""
  modification-date"Fri, 12 Dec 2003 021708 -0
• 500"
• Content-Type application/applefile NAME
• AAUWBwACAAAAAAAAAAAAAAAAAAAAAAAAAAMAAAADAAAAPgAAAA
  0AAAAJAAAASwAAACAAAAAIAAAA
• awAAABBNb2JpSG9jMDQucGRmAAAAAAAAAAAAAAAAAAAAAAAAAA
  AAAAAAAAAAAAAAAAAHaGbB2vh
• pEttDAAHaVg
• --_-1140908113_D
• Content-Disposition attachment
  filename"MobiHoc04.pdf"
• Content-Transfer-Encoding base64
• Content-Type application/octet-stream
  NAMEMobiHoc04.pdf
• JVBERi0xLjQKNSAwIG9iago8PCAvUyAvR29UbyAvRCAoc2VjdG
  lvbi4xKSAPgplbmRvYmoKOCAw
• IG9iagooTW90aXZhdGlvbikKZW5kb2JqCjkgMCBvYmoKPDwgL1
  MgL0dvVG8gL0QgKHNlY3Rpb24u
• MikgPj4KZW5kb2JqCjEyIDAgb2JqCihSYWRpb3MgaW4gVGhlb3
  J5IGFuZCBQcmFjdGljZSkKZW5k
• b2JqCjEzIDAgb2JqCjw8IC9TIC9Hb1RvIC9EIChzZWN0aW9uLj
  MpID4CmVuZG9iagoxNiAwIG9i

base64 map three binary bytes into four ASCII
characters.
8
Message Transfer
One SMTP daemon talks to the next one over a TCP
connection. The mail travels across various SMTP
gateways until it arrives at the recipients
location. Each SMTP gateway buffers messages on
disk and may retransmit them for days until the
next daemon can receive them.
Question Why isnt the message delivered
directly to the receivers host?
9
IMAP
Client/Server protocol over a TCP
connection. Commands allow client to FETCH,
STORE, DELETE, and EXPUNGE. Messages on the
server are marked as Seen, Answered, Deleted, and
Recent.